This invention relates to couplings in general and is particularly directed to a sealing plug for use in a torque transmitting slip spline assembly.
Slip spline assemblies of the type to which the invention relates typically comprises a yoke having a splined bore for slidably receiving a splined portion of a stub shaft. In these applications it is necessary to provide lubrication between the mating sliding splines. The spline connection may be lubricated for life at assembly, or the yoke may have a lubrication fitting for periodically replenishing lubricant. Usually, the body end of the slip yoke is sealed with a plug to retain the spline lubricant. The plug may be either solid or vented. The method of sealing employed for a spline connection generally depends on its specific design as well as its application. For example, in an internally splined slip yoke used at the transmission output shaft of a vehicle, a solid plug is used at the body end and a boot type seal is provided at the hub end of the slip yoke to protect the splines from dust, dirt, and other foreign matter. In this type of application, it is common practice to remove one of the spline teeth to facilitate the back and forth flow of lubricant during stroking. In applications having a seal retained on the slip yoke hub end in direct sealing contact with the stub shaft, a vented plug is used to maintain lubricant on the splines and prevent a pressure build-up when the stub shaft slides towards the closed end of the slip yoke.
In the past, numerous methods have been disclosed for retaining sealing plugs in slip yoke bores. The plugs also have taken many shapes. The more conventional types include a Welch plug, which consists of a flat annular disc, and a cup-shaped plug. In each case, the plug is pressed into the hub end of the slip yoke bore and retained in place by welding, staking, or a suitable epoxy cement.
While plugs of the above type function satisfactorily, they require additional operations after being pressed in place for positive retention in the slip yoke bore.